JP3351153B2 - Manufacturing method of semiconductor pressure sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor pressure sensor, and more particularly to a method of manufacturing a semiconductor pressure sensor in which a semiconductor pressure sensor chip is connected to leads via wires.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing an example of a conventional semiconductor pressure sensor for a vehicle. Semiconductor pressure sensor chip 1
In order to measure the pressure of a fluid such as gas or oil, a diaphragm 1a that converts the pressure into a stress and a strain gauge (not shown) that converts the stress of the diaphragm 1a into an electric signal are formed.

[0003] The semiconductor pressure sensor chip 1 is provided to reduce external stress applied to the semiconductor pressure sensor chip 1.
The pedestal 2 is joined to the upper surface of the pedestal 2 by solder 4 on one end surface (upper end surface) of a metal pipe 3. The pipe 3 is fixed to the stem 5 by glass 6 so as to penetrate substantially the center of the substantially flat stem 5 serving as a base of the package of the semiconductor pressure sensor. An electric signal output from the strain gauge of the semiconductor pressure sensor chip 1 is fixed to the stem 5 by a glass 6 so as to penetrate the stem 5 via a wire 7 connected to the semiconductor pressure sensor chip 1. From the lead 8 of the device. A cap 9 that covers the semiconductor pressure sensor chip 1 and the like is joined to the stem 5, and a space sealed by the stem 5 and the cap 9 serves as a pressure reference chamber 10.

In the semiconductor pressure sensor configured as described above, the pressure of the gas or liquid to be measured is transmitted to the diaphragm 1a of the semiconductor pressure sensor chip 1 through the pipe 3 and the through hole 2a of the pedestal 2, and the pressure is measured. The diaphragm 1a bends in accordance with the pressure difference from the pressure inside the reference chamber 10, and an electric signal is output from the strain gauge.

[0005]

In the conventional semiconductor pressure sensor shown in FIG. 3, the connection between the semiconductor pressure sensor chip 1 and the lead 8 is performed by wire bonding using the wire 7, but the wire 7 is In the case of connection to the upper end surface, the wire bonding process becomes extremely unstable, and many breaks or poor crimping of the wire 7 (such as a state where only a small portion of one end of the wire 7 is crimped to the upper end surface of the lead 8) occurs. Was. This is Au as wire 7
This is because the wire bonding is performed by thermocompression bonding while applying ultrasonic vibration to the wire 7 using the wire. That is, the upper ends of the wires 7 and the leads 8 (usually Au
When bonding (plated), the ultrasonic vibration applied to the wire 7 from the capillary of the wire bonder is transmitted to the lead 8 and the lead 8 resonates (vibrates), so that a wire bonding failure has occurred.

The substantially rod-shaped lead 8 is made thicker, and the height of the upper end surface of the lead 8 from the upper surface of the stem 5 (hereinafter referred to as the lead 8)
Is reduced, the rigidity of the lead 8 is increased, the natural frequency of the lead 8 can be sufficiently increased, and the resonance of the lead 8 or the vibration of the tip of the lead 8 is suppressed during wire bonding. As a result, wire bonding defects can be reduced, but it is difficult to increase the height of the lead 8. In a general wire bonder, for example, when the lead diameter is about φ0.5 mm, the height of the lead 8 is about 1.2mm was the limit. This is because when the height of the lead 8 is increased to about 1.2 mm, the yield of the wire bonding process is reduced to about 90%, and the branch point of mass production feasibility is reached in terms of production cost.

On the other hand, the pedestal 2 on which the semiconductor pressure sensor chip 1 is bonded to the upper surface relieves the external stress on the semiconductor pressure sensor chip 1 and reduces the external stress (the thermal stress generated due to the difference in the coefficient of thermal expansion between different materials). Stress) to reduce output fluctuations and increase measurement pressure detection accuracy.
If the thickness of the pedestal 2 was sufficiently increased, a semiconductor pressure sensor with higher detection accuracy could be obtained. However, in order to increase the thickness of the pedestal 2 sufficiently, the height of the lead 8 must be increased, and there is a problem that the yield of wire bonding is reduced. This is because the height difference between the upper end surface of the lead 8 and the wire bonding surface of the semiconductor pressure sensor chip 1 was limited to a maximum of about 0.5 mm in practical use. When the difference in height from the wire bonding surface of the wire bonder becomes large, the bonding point of the wire bonder is recognized, or
This is because it is difficult to adjust the bonding state of the capillaries (adjustment of the degree of balance of the capillaries), and there is a problem that wire bonding defects increase. Therefore, lead 8
When the thickness of the pedestal 2 is increased in order to reduce the difference in height between the upper end surface of the semiconductor pressure sensor chip 1 and the wire bonding surface of the semiconductor pressure sensor chip 1 to within about 0.5 mm, the height of the leads 8 must also be increased. It is.

[0008] The present invention has been made in view of the above problems,
Its purpose is to stably perform wire bonding for connecting a semiconductor pressure sensor chip and a lead with a high yield, reduce output fluctuation due to external stress, and
It is an object of the present invention to provide a method of manufacturing a semiconductor pressure sensor capable of improving the detection accuracy of a measurement pressure.

[0009]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor pressure sensor, comprising: a semiconductor pressure sensor chip; a stem supporting the semiconductor pressure sensor chip; A method for manufacturing a semiconductor pressure sensor, comprising: a wire connected to a chip, and a lead connected to the wire and supported by the stem so as to penetrate the stem, wherein the wire of the lead is connected to the wire. A substantially disk-shaped flange is formed near the end on the side of the lead, and a shaft portion of the lead passes therethrough.
The tip is open in the tip direction and the tip is bifurcated.
It has a substantially strip-shaped support plate with a
The plate is approximately parallel to its plane and substantially perpendicular to the length of the support plate.
A straight horizontal rotation axis is attached and centered on the horizontal rotation axis
So that it can rotate freely and lead the support plate
Prepare a supporting device that can move in the direction of approaching and separating from
First, support the lead shaft to pass the lead shaft
The plate is moved in a direction close to the leads, then the support plate
To rotate around the horizontal rotation axis to support the lower part of the lead flange.
Wire bonding to the top end of the lead.
And then rotate the support plate in the opposite direction about the horizontal rotation axis.
To separate from below the flange of the lead, and then remove the support plate.
And it is characterized in Rukoto is moved in the direction away from the lead.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor pressure sensor, comprising: a semiconductor pressure sensor chip, a stem supporting the semiconductor pressure sensor chip, a wire connected to the semiconductor pressure sensor chip, and a connection to the wire. A method for manufacturing a semiconductor pressure sensor, comprising: a lead supported by the stem so as to penetrate the stem.
The shape of the tip is partially cut out in a semicircular shape in plan view.
The lead positioning recess corresponds to the lead protruding from the stem
The core is formed close to the lead.
It can move in the contact and separation directions,
Prepare an electromagnet support device that holds so that force is generated,
First, insert the iron core so that the lead fits into the lead positioning recess.
Move in the direction close to the lead and then support the electromagnet
Energize the device to attract and support the lead on the iron core, and then
Wire bonding to the upper end of the
Stop energizing the magnet support device and release the lead suction
And moving the iron core in a direction away from the lead .

[0011]

[Function] For wire bonding to the upper end surface of the lead,
Using an Au wire with a diameter of about 30 μm, thermocompression bonding and ultrasonic bonding are used in combination, and a load of several tens g is applied to the joint. At this time, since ultrasonic energy is applied, the rigidity of the lead must be increased so as not to cause resonance (vibration). A flange portion is formed in the vicinity of the connection end), and when the wire is wire-bonded to the upper end surface of the lead, the flange portion is supported by a supporting device to perform wire bonding. It is. As a result, resonance (vibration) of the lead can be suppressed, and the loss of ultrasonic energy can be reduced, so that wire bonding can be performed stably.

According to a second aspect of the present invention, in the method of manufacturing a semiconductor pressure sensor, when the wire is wire-bonded to the upper end surface of the lead, a portion such as an iron core provided on the electromagnet support device is brought into contact with the lead. The wire bonding is performed by attracting and supporting the lead by magnetic force at a portion such as the iron core. As a result, resonance (vibration) of the lead can be suppressed, and the loss of ultrasonic energy can be reduced, so that wire bonding can be performed stably. In the case of this method, a lead material containing a ferromagnetic element (for example, iron, cobalt, nickel, or the like) is used.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for manufacturing a semiconductor pressure sensor according to the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a state in which a stem on which a semiconductor pressure sensor chip and leads and the like are mounted is fixed on a stage of a wire bonder (not shown), and the leads are supported by a supporting device and wire bonding is performed. Is a sectional view, and (b) is a plan view showing only a part of a lead and a supporting device. However, the same components as those shown in FIG. 3 are denoted by the same reference numerals.

First, the structure of the semiconductor pressure sensor in the wire bonding step will be described. The semiconductor pressure sensor chip 1 is joined to an upper surface of a pedestal 2 for relieving external stress applied to the semiconductor pressure sensor chip 1, and the pedestal 2 is soldered on one end surface (upper end surface) of a metal pipe 3. 4 are joined. The pipe 3 is fixed to the stem 5 by glass 6 so as to pass through substantially the center of the stem 5 serving as the base of the package of the semiconductor pressure sensor 1. An electric signal output from the strain gauge of the semiconductor pressure sensor chip 1 passes through a stem 6 via a wire 7 connected to the semiconductor pressure sensor chip 1 so as to pass through the stem 5.
Thus, the lead 11 is taken out of the lead 11 fixed to the stem 5.

A substantially disk-shaped flange 11a is formed at the upper end of the lead 11 (the end connected to the wire 7). FIG. 1 shows an example in which one end of the lead 11 is processed into a nail head shape by a method such as crushing one end of the lead 11 to form a substantially disk-shaped flange portion 11a, but is not limited to the embodiment. is not.

Reference numeral 12 denotes a substantially strip-shaped support plate which is a part of the support device. The support plate has a bifurcated distal end portion, and has a lead introduction groove 12a opened in the distal direction. The width of the lead introduction groove 12a is set so that the shaft (pattern) of the lead 11 passes therethrough. The support plate 12, which is a part of the support device, is configured to be movable. However, FIG. Or the configuration for holding the support plate 12 so as to be movable) is not shown. The support plate 12 has a horizontal rotating shaft 13 substantially parallel to the surface direction and substantially perpendicular to the length direction of the support plate 12.
The support plate 12 is configured to be rotatable about the horizontal rotation shaft 13 (a configuration for supporting the horizontal rotation shaft 13 is not shown).

As described above, a support device including the lead 11 and the support plate 12 is constructed, and the lead 11
When wire bonding to the upper end surface of the support plate 12, the support plate 12 is moved so that the lead 1 is inserted into the lead introduction groove 12a of the support plate 12.
The support plate 12 is rotated about a horizontal rotation shaft 13 through a shaft (shaft) portion of the lead 11, and the flange 11 a of the lead 11 is supported from below by the bifurcated portion of the support plate 12.
Wire bonding to the upper end surface of the substrate. This allows
Since the resonance (vibration) of the lead 11 due to the applied ultrasonic energy can be suppressed, the wire bonding can be stably performed. After the wire bonding, the support plate 12 is rotated and moved to separate from the lead 11. However, in the embodiment shown in FIG. 1, the support device is described as being configured to rotatably hold the support plate 11, but the present invention is not limited to the embodiment. Further, the shape of the support plate 11 is not limited to the embodiment.

Another embodiment of the semiconductor pressure sensor of the present invention will be described with reference to FIG. 2A and 2B are views showing a state of a wire bonding step, wherein FIG. 2A is a cross-sectional view, and FIG. 2B is a plan view showing a peripheral portion of a lead. However, since the configuration of the semiconductor pressure sensor is substantially the same as the configuration shown in FIG. 3, the same components are denoted by the same reference numerals, and detailed description will be omitted.

In FIG. 2, reference numeral 14 denotes an iron core, which is one configuration of an electromagnet device (not shown) provided on an electromagnet support device (not shown). The iron core 14 is movably held by the electromagnet support device. The leading end portion of the iron core 14 is formed in a substantially flat plate shape, and the leading end portion has a lead positioning recess 14 having a shape in which the iron core 14 is locally cut out in a substantially semicircular shape in plan view.
a is formed corresponding to each lead. The electromagnet device is configured such that a magnetic force is generated by energizing the electromagnet device, and the ferromagnetic material can be attracted to the iron core 14.

The lead 8 is made of a ferromagnetic material (for example, Kovar, nickel, iron, or an alloy thereof), and the upper end surface to which the wire 7 is bonded is subjected to a treatment such as Au plating. Have been. In general, when the lead 8 is fixed to the stem 5 via the glass 6, Kovar having a coefficient of thermal expansion close to that of glass is used as the material of the lead 8.

As described above, the electromagnet support device and the leads 8 are configured, and each lead 8 is fitted into the lead positioning recess 14a, and the iron core 14 is moved so that the iron core 14 comes into contact with the lead 8. By energizing the electromagnet device, the lead 8 is attracted and supported by the iron core 14 to perform wire bonding. Thereby, the vibration (resonance) of the lead 8 due to the applied ultrasonic energy can be suppressed, and the wire bonding can be stably performed. After the wire bonding is completed, the power supply to the electromagnet device is stopped and the iron core 1
4 is separated from lead 8. The shape of the iron core 14 is not limited to the embodiment.

[0022]

As described above, according to the method of manufacturing a semiconductor pressure sensor according to the first aspect, the flange is provided near the end of the lead on the side to which the wire is connected, and the flange is provided. By connecting the wire to the lead while being supported by the supporting device, the vibration (resonance) of the lead due to the applied ultrasonic energy can be suppressed, so that the wire bonding can be performed stably and the yield can be improved. . Further, since the height of the lead can be considerably increased and the pedestal can be made thicker, output fluctuation due to external stress applied to the semiconductor pressure sensor chip can be reduced, and detection accuracy of the measured pressure can be increased. .

According to the method of manufacturing a semiconductor pressure sensor according to the second aspect, the lead is connected to the lead while being attracted and supported by the electromagnet supporting device, so that resonance of the lead due to the applied ultrasonic energy ( (Vibration) can be suppressed, so that wire bonding can be performed stably and the yield can be improved. Further, since the height of the lead can be considerably increased and the pedestal can be made thicker, output fluctuation due to external stress applied to the semiconductor pressure sensor chip can be reduced, and detection accuracy of the measured pressure can be increased. .

[Brief description of the drawings]

1A and 1B are views showing one embodiment of a method for manufacturing a semiconductor pressure sensor according to the present invention, wherein FIG. 1A is a cross-sectional view and FIG. 1B is a plan view.

FIGS. 2A and 2B are views showing different embodiments of the method for manufacturing a semiconductor pressure sensor according to the present invention, wherein FIG. 2A is a cross-sectional view and FIG.

FIG. 3 is a sectional view showing an example of a conventional semiconductor pressure sensor.

[Explanation of symbols]

 Reference Signs List 1 semiconductor pressure sensor chip 5 stem 7 wire 8, 11 lead 11a flange 12 support plate (part of support device) 14 iron core (part of electromagnet support device)

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-194432 (JP, A) JP-A-1-183130 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 9/04 101 H01L 29/84

Claims (2)

(57) [Claims] 1. A semiconductor pressure sensor chip, a stem supporting the semiconductor pressure sensor chip, a wire connected to the semiconductor pressure sensor chip, and supported by the stem so as to penetrate the stem connected to the wire. And a method of manufacturing a semiconductor pressure sensor having a lead, wherein a substantially disk-shaped flange is formed near an end of the lead on the side to which the wire is connected , and
Open in the tip direction so that the shaft part passes, and the tip part is
A substantially strip-shaped support plate with a bifurcated lead introduction groove
This support plate is substantially parallel to the surface direction and
A horizontal rotating shaft that is almost perpendicular to the length
Attached so that it can rotate around the flat rotation axis,
Support that can move the support plate toward and away from the lead
Prepare the device. First, insert the lead shaft into the lead introduction groove.
Move the support plate in the direction close to the lead so that
Next, the support plate is rotated about the horizontal rotation axis to
Support the lower part of the collar, then wire to the top end of the lead
Perform bonding, and then move the support plate
Pivots in the opposite direction to the center, separates from below the flange of the lead, and
To, a method of manufacturing a semiconductor pressure sensor according to claim Rukoto is moved in the direction away the support plate from the lead. 2. A semiconductor pressure sensor chip, a stem supporting the semiconductor pressure sensor chip, a wire connected to the semiconductor pressure sensor chip, and supported by the stem connected to the wire and penetrating the stem. Manufacturing method of a semiconductor pressure sensor provided with a set lead, wherein the front end portion is locally cut out in a substantially semicircular shape in plan view
-Shaped lead positioning recess on the lead protruding from the stem
With a correspondingly formed core, this core
It can move in the approaching and separating directions, and
An electromagnet support device is provided to hold magnetic force.
First, make sure that the lead fits into the lead positioning recess
Move the heart in the direction close to the lead, then the electromagnet
Energize the support device to attract and support the lead on the iron core,
Wire bonding to the upper end surface of the lead.
To stop the energization of the electromagnet support device and
Open and move the iron core away from the lead
The method of manufacturing a semiconductor pressure sensor according to claim Rukoto is.